On Linux, I can't use a mouse click to scroll through the backlog

[armadev]

On Linux, once I have more than one screen worth of messages with somebody, I'd like to be able to click on the little thing on the right side of the screen that looks like a scrollbar, to read the earlier messages.

I can get to them with the newfangled "two fingers on the trackpad moving up" approach, but it sure would be nice if clicking on something at the top of what I thought was a scrollbar would work too.